«From Latha Bhaskar, Ashoka Trust for Research in Ecology and the Environment, Thiruvananthapuram, Kerala Posted 25 June 2009 I work with the Ashoka ...»
Solution Exchange for the Water Community
Query: Use of R. O. Systems for Providing Safe Drinking Water
- Experiences; Referrals
Compiled by Nitya Jacob, Resource Person and Sunetra Lala, Research Associate
Issue Date: 17 August 2009
From Latha Bhaskar, Ashoka Trust for Research in Ecology and the
Environment, Thiruvananthapuram, Kerala
Posted 25 June 2009
I work with the Ashoka Trust for Research in Ecology and the Environment (ATREE), Kerala, on wetland conservation. Currently, I am working on the Vembanad project, concentrating on the area (both land and lake) to the south of Thanneermukkom barrage of the Vembanad wetland system in Kerala. We regularly monitor the water quality of the lake. We have found the presence of large concentrations of microbial pathogens, pesticides and other chemical contaminants in the water. Water borne diseases are prevalent in this area and recently there was a cholera outbreak killing 12 people.
People in the 17 Gram Panchayats surrounding the lake depend on its water for all their domestic purpose, including cooking and drinking. They have no choice, as the piped water supply coverage is just 20%. This water comes from far off places (Tiruvalla) and is unsafe due to the leaks in the pipes, which pass through the lake. During the summer, drinking water is supplied by 35 boats, each carrying 2400 litres of water. Rainwater harvesting units exist in this area, but are not very popular as most households have thatched roofs and little space to construct storage tanks.
To provide potable drinking water to these people, ATREE plans to install a few Reverse Osmosis (R.O.) plants in selected places to filter lake water. However, these should be reliable. If they prove to be successful, they will pave the way for more such local and decentralised units. I want to learn more about R.O. plants to implement this model.
I request Community members to please share their inputs on the following:
What are the experiences of using R.O. systems? Please share details regarding their cost effectiveness, longevity, O&M costs, safe-guards, technology diversifications, if any What area-specific, decentralized approaches can be adopted in places like Kuttanad, Kerala which is a waterlogged area and below the sea level?
Please provide details of agencies and institutions installing R.O. systems.
Your inputs will help ATREE develop and implement this model for providing drinking water in these Panchayats.
Responses were received, with thanks, from
1. Ramakrishna Nallathiga, Centre for Good Governance, Hyderabad
2. Sree Hari N., Byrraju Foundation, Hyderabad
3. J. Saravanan, DHAN Foundation, Chennai
4. K. D. Bhatt, GSFC Science Foundation, Vadodara
5. Amitangshu Acharya, Arghyam, Bangalore (Response 1) (Response 2)
6. Jim Baldwin, Consultant, Bahrain
7. R. K. Srinivasan, Centre for Science and Environment, New Delhi (Response 1) (Response 2)
8. Latha Bhaskar, Ashoka Trust for Research in Ecology and the Environment, Thiruvananthapuram (Response 1) (Response 2)
9. Sumita Ganguly, Independent Consultant, New Delhi
10. Shibu K. Mani, Division of Disaster Management, Mahatma Gandhi University, Kottayam
11. Sacchidananda Mukherjee, National Institute of Public Finance and Policy (NIPFP), New Delhi
12. Jasveen Jairath, Water Sector Professional, Hyderabad (Response 1) (Response 2) (Response 3) (Response 4) (Response 5)
13. Ajit Seshadri, The Vigyan Vijay Foundation, New Delhi (Response 1) (Response 2)
14. Amitava Basu Sarkar, Himalayan Institute Hospital Trust, Dehradoon
15. Terry Thomas, Wilbur Smith Associates, Bangalore
16. K.A.S. Mani, Andhra Pradesh Farmers Managed Groundwater Systems (APFAMGS), Hyderabad
17. Dinesh Kumar, Institute for Resource Analysis and Policy, Hyderabad (Response 1) (Response 2) (Response 3)
18. Pavitra Singh, People’s Science Institute, Dehradoon
19. Nitya Jacob, United Nations Children’s Fund (UNICEF), New Delhi
20. Salahuddin Saiphy, Centre for Science and Environment (CSE), New Delhi
21. Salathiel R Nalli, United Nations Children’s Fund (UNICEF), Hyderabad
22. Atul Rawat, DMV Business and Market Research Pvt. Ltd., Hyderabad
23. Uday Bhawalkar, Bhawalkar Vermitech Pvt Ltd, Pune
24. Gary Grunder, Association for Needy And Neighbouring Downtrodden, Guntur (Andhra Pradesh)
25. N. C. S Seema, WaterHealth India Pvt. Ltd, Secunderabad
26. R K Srinivasan, Centre for Science and Environment (CSE), New Delhi
27. Avani Mohan Singh, Haritika, Jhansi
28. Jared Buono, Watershed Management Group, Chennai * *Offline Contribution Further contributions are welcome!
Summary of Responses Comparative Experiences Related Resources Responses in Full Summary of Responses Reverse Osmosis (RO) is a relatively modern technique for purifying drinking water. The system forces water under pressure through an ultrafine filter (usually a membrane), retaining the impurities on one side while pure water collects on the other. Several organisations have set up RO systems in villages and slums to treat water for drinking, and provide it to communities at 10paise per litre.
A RO system for a group of around 250 households, that can process around 500 litres of water an hour (LPH), costs around Rs 125,000. This uses about 2 kilowatts of power, or around 1200 units, per month. The cost of purifying water from a plant of this scale works out 5 paise per litre; selling it at 10 paise per litre will enable the operator to recover the capital costs as well as some of the running costs.
However, RO plants are a costly option and generate large quantities of wastewater. The concentration of dissolved solids in this wastewater is 50 per cent to 100 per cent higher than the input water, making its disposal a problem. Small RO plants have low efficiency levels, purifying just 5-15 per cent of the water that passes through them; this means they need about 10 litres of raw water to produce just one litre of pure water. Finally, they are power-hungry and in rural areas, where power is short, they may not run to capacity.
The filtration membrane is the plant’s most delicate and expensive part. It may be necessary to pre-treat water before putting it through the RO system to prolong the membrane’s life. In the area under consideration around Vembanad Lake, the water is brackish and has a high bacterial load. It needs a multi-stage treatment process before it can be safe to drink.
RO systems are supposed to remove all dissolved solids and bacteria, but to make doubly sure, the water being supplied to the RO system can be pre-treated with ultra-violet to first kill the bacteria. In this way, the wastewater from all the RO systems in the 17 gram panchayats (assumed around 100 units) will have a very marginal impact on the ecology of the lake, if it is discharged directly into the lake without treatment. In the Vembanad instance, salt will be the main contaminant of the wastewater. If UV pre-treatment kills the bacteria, they will not add to the pollutant load in the wastewater.
The Byrraju Foundation has set up RO plants in the East Godavari and Krishna districts of Andhra Pradesh. Each village has a plant capable of providing 1000 LPH, set up at a cost of Rs 650,000. People get 2-3 litres of drinking water a day for 12.5 paise per litre. The State Government is planning to install RO plants in all villages to provide safe drinking water. The Central Salt and Marine Chemicals Research Institute has installed one RO plant in Bhavnagar, Gujarat. In Rajasthan, the Piramal group has launched a programme called Sarvajal to provide drinking water to villages where groundwater is undrinkable.
In the Ramanathpuram district, Tamil Nadu, the State Government set up a desalination plant to provide 15 litres of water per day to 296 people. The Rs 35.48 crore venture ran aground over the high cost of changing the membranes. Each of the 168 membranes of the unit costs Rs 50,000. The Naandi Foundation has installed RO plants in several villages of Punjab and Andhra Pradesh at a cost of Rs 12-18 lakh per piece; they supply water to consumers at 10 paise per litre. Cherukunnu Town in the Kannur district of Kerala gets water from a RO plant.
There are several alternatives to RO systems for safe drinking water. The most popular is rainwater harvesting (RWH). The Vembanad lake region gets around 3,000 mm of rainfall per year. Even though most houses have thatched roofs, the people can use plastic sheets to capture enough rainwater to meet their needs for drinking water needs. The BAIF Institute for Rural Development-Karnataka has set up rooftop RWH systems in several villages in Karnataka where groundwater is contaminated with fluoride.
In Tamil Nadu, several communities have renovated their traditional water sources, called ooranis (ponds). As the sub-surface water level is high, people can construct shallow clay- or plastic-lined ponds to catch rainwater in the Vembanad region. This will prevent the saline groundwater from mixing with the water in the pond. Several low-cost methods can be used to treat the pond water for drinking.
One such is the slow-sand filter developed by the Centre for Environmental Studies of Anna University, Tamil Nadu. This has reduced the coliform count by 90 percent in six pilot projects of oorani renovation in the Kancheepuram and Ramanathpuram districts of the state. The DHAN Foundation has demonstrated use of these filters with ooranis.
Solar disinfection, sodis, is another inexpensive method to purify water. The Mahatma Gandhi University, Kottayam, Kerala, is working on a way to use this way to cleanse water of bacteria and dissolved solids. It is evaluating the method to make pond water safe to drink near Jodhpur.
Action for Food Production has designed a horizontal roughing filter to remove suspended particles and bacteria. It also uses plants to fix salts such as nitrates, chlorides and sulphates.
However, this phyto-remediation process needs a lot of space.
The Association for Needy and Neighbouring Downtrodden, Guntur, Andhra Pradesh, is working on a system that uses a combination of oxidation and reduction using solar powered electrolysis to remove dissolved salts. Others have used a combination of filters and chlorination for water treatment. In Gujarat, an NGO advises a group of organizations that work with communities to ensure drinking water security in the Kutch region.
RO systems can be an immediate solution to the drinking water problem for the people in the 17 gram panchayats. However, the communities have to work out a method of maintaining the systems. The pricing of water should be such that they operator can recover the cost of running the plants. A panchayat-appointed committee can oversee the service delivery in terms of both quantity and quality. It will be crucial to maintain equity while providing water; one way to ensure inclusion of the poor is to issue all residents cards that entitle them to a daily quote of water. This will prevent the rich residents from buying more than their entitlement and depriving the poor of theirs.
Before setting up any plants, the agency must assess the pollution load and concentration in the region to determine the best treatment methods. It may be necessary to pre-treat water before RO treatment to get the best results and extend the life of the RO membranes. It will have to educate communities on the advantages of RO systems visavis other sources of water to ensure their adoption and maintenance.
Comparative ExperiencesAndhra Pradesh
RO Plants by Byrraju Foundation, East Godavari and Krishna districts (from Ramakrishna Nallathiga, Centre for Good Governance, Hyderabad) Water in several villages in these districts is saline and has a high concentration of dissolved minerals. The Byrraju Foundation installed RO plants in several villages, sharing the costs with the community. It trained two people to operate the plant. It has set up 29 plants in 80 villages that meet the drinking water needs of 380,000 people. The operator charges Rs 1.5 for 12 litres of water, that is supplied in food grade HDPE bottles. Read more.
Naandi supplies drinking water through RO, (from Jasveen Jairath, Water Sector Professional, Hyderabad, response 1) People in several districts of Andhra Pradesh used to drink water contaminated with pesticides, and suffer from a variety of diseases. Naandi Foundation installed RO plants, along with its technology partner Tata Projects and Water Health International, in selected villages. It has covered 390,000 households in the state over the past several years. People pay 10 paise per litre for the water. Read more.
Oxidation/reduction process to remove dissolved minerals, Guntur (from Gary Grunder, Association for Needy And Neighbouring Downtrodden) Groundwater in the district is heavily laced with minerals. The organisation is developing a process of flocculating these out of the water through a process of both oxidation and reduction using solar-power electrolysis. They have added silver as this has anti-septic properties. Their system treat about 200 litres of water a day in bright sunlight that is free of harmful dissolve minerals, at minimal cost. Read more.
Safe Drinking Water Plant completes one year, Gidderbaha, Muktsar district (from Jasveen Jairath, Water Sector Professional, Hyderabad, response 1) People in this region suffered from high rates of cancer caused by water pollution. The Naandi Foundation and its technology partner Tata Projects set up 63 community-based RO in 57 villages throughout the block. The Gidderbaha Safe Drinking Water Project was part of the Public Private Partnership (PPP) between the panchayats, government and the Foundation. Now, more than 150,000 people in the block get water that is safe to drink. Read more.
Cherukunnu gets drinking water from RO, Cherukunnu, Kannur district (from Dinesh Kumar, Institute for Resource Analysis and Policy, Hyderabad, response 2 ) The village of Cherukunnu in the coastal Kannur block of the district was short of drinking water.
The gram panchayat installed RO plant to provide residents with safe drinking water. It is managed by the panchayat. The local people have found a way to dispose off the wastewater from the plant. It has solved their drinking water problem. Read more.